A method and an apparatus for production and identification of valuable documents such as debit cards is disclosed in Swiss Patent No. 594,935. (See for example, column 4, lines 1 through 21)
It is the object of the present invention to improve the known method and apparatus for the mechanical validation of valuable documents. The main object of the method and apparatus being the recognition of forgeries, so that forgeries can be better recognized and so that deliberate and accidental manipulations of genuine valuable documents in validation machines (e.g. readers) can be prevented.
Valuable documents include documents that can be read by machine. Such documents carry intelligence (i.e. information) that can be cancelled by machine. Typically, such documents are used for cashless payments for goods and services and may include, for example, transportation and entrance tickets, and credit cards.
In the latter case, the credit card often includes a multitude of cash value units in the form of coded intelligence that are used for the prepayment of services, for example, for prepayments of electricity, gas or water usage or for prepayment of a telephone call in a public phone booth. If the service is rendered, the value units that comprise coded intelligence are read and validated by a mechanical reader in order to be totally or partially cancelled according to the value of the rendered service.
So far, considerable expenditures have been taken, for instance by using holograms, in order to render valuable documents forgery-proof. Since reading and cancellation of cash value units heretofore occurred independent of each other, it has been relatively easy to read valuable documents without cancelling value units in accordance with services rendered. This was done by suppressing the cancellation by some manipulation of the cancellation process. The cancellation can for instance be avoided by removing the cancellation head in a card reading device, by a defective cancellation head, by pulling out the value document quickly before the cancellation has started or by short-circuiting the cancellation etc. Thus, by using the same valuable document several times, the service may be rendered without being paid for. Desirably, this should be prevented.